I'm looking for a down jacket that will keep me warm in the winter for having stopped walking and setting up camp, taking a break, but also for sitting outside at the pub and queueing in the cold, i.e. activities where I'm not moving around at all.

It's around 0C in the evenings and nights here in the UK at the moment and I've been testing out a Patagonia Down Sweater. When I've been walking around for 30 minutes it can get quite warm and toasty especially going up hills. However when I first put it on and walk out the door, I'm cold.

Can you judge a jacket by how warm it is when you first put it on? Or do you need to move around first to build up the heat? Is it possible to have a jacket that is so warm that you don't need to exert yourself first, but you can still be warm standing/sitting in the cold?

  • 1
    I've recently bought a cheap (Peter Storm) down jacket, and I tend to wear it when I stop moving. It takes a minute or two to feel warm, but that's without expending effort. I deliberately went for quite a light fill. Have you tried doing something similar? Mine has a hood BTW, which helps a lot (as does a hat, but the hood keeps draughts off the back off my neck)
    – Chris H
    Commented Jan 23, 2023 at 12:08
  • What model is your Peter Storm jacket and what temperature do you use it in and stay warm while static? Does it keep you warm for hours, or just a few minutes as your body gets cooler?
    – Tom
    Commented Jan 23, 2023 at 15:51
  • it's a bit soon to tell - I bought it a year ago but haven't worn it much. The last few times I've worn it I've been pretty wet in temperatures just above freezing, not warm to start with, then got cold before I had it out of my saddle bag and on me, then warmed up (e.g. stopping for a quick lunch while mountain biking, barely sheltered from the wind). It's a Packlite Alpinist. The last few are being sold off cheap if they're your size!
    – Chris H
    Commented Jan 23, 2023 at 16:04
  • Tom's current Patagonia Down Sweater is almost definitely warmer than this Peter Storm Jacket. Looks like more, and higher fill, down.
    – noah
    Commented Jan 23, 2023 at 18:56
  • @noah I'm not surprised. I went for a very light one partly because I run pretty warm. partly to pack down small, and partly knowing my use case as an extra layer for cold periods like stops and descending (by bike or on foot). I mentioned it because even a lighter one than Tom has warms up fast, but not instantly assuming I'm cool when I put it on, and thought his better one should behave in a similar way. Also mine was really cheap in the sales last year
    – Chris H
    Commented Jan 23, 2023 at 21:47

1 Answer 1


Let's start with some general technical info, and then we'll get to the specific questions.

One way to judge the warmth of a down/synthetic "down" jacket is the type and amount (by weight) of insulation. Type is easy to figure out. Brands will say if it is down or synthetic, and typically the fill-power of the down or the type of synthetic. In terms of amount, some insulated jackets from outdoors oriented brands will just straight give you a fill amount in terms of g/m^2 for synthetic and total g/oz for down on the product page. Anecdotally it seems to have gotten less common in the last 5 years though.

Let's use Feathered Friends Eos as a down example. It says it has 4oz of fill of high quality 900+ fill-power Down. Fill-Power is a numerical measure of expansion/loft of the down (higher number = more loft = warmer by weight). While there can be some exceptions based on shell fabric/construction/fit this jacket will be warmer than a jacket with less insulation, or with lower fill insulation of the same weight. But 9oz of 750+ fill-power down is going to be warmer despite a lower fill-power. To compare jackets it is a good rough estimate to just multiply the two numbers with higher being better.

Let's use Arctery'x Atom LT as a synthetic example. It says it has 60g/m^2 Coreloft insulation. Coreloft is their in-house synthetic insulation. All the different types of synthetic insulation from reputable outdoor brands are relatively similar in warmth. The quantity is the key number to look at, and, exactly as you'd probably imagine, higher is warmer. Since synthetic insulation is almost always manufactured as big sheets that are cut to shape for jackets you'll see the measurements as g/m^2.

Why do they measure down/synthetic fill differently? Primarily because of the practical manufacturing difference. One is a loose insulation whereas the other is flat sheets. But this doesn't mean you can't compare. Anecdotally, I would say jackets with 3-4oz of 800-900FP down are about as warm as 100g/m^2 jackets. My Cerium (3-4oz of 850) is good for 15-20F degrees more low-activity warmth than my Atom LT (60g/m^2).

A less scientific way to judge warmth is price. You get what you pay for mostly rings true with insulation. It's of course non-linear. But a $100 down jacket will not be as warm as a $300 down jacket. Or at least I haven't found one yet.

Can you judge a jacket by how warm it is when you first put it on? Or do you need to move around first to build up the heat?

It's very hard to judge a jacket by how "warm" it is when you first put it on because it's a very unscientific measurement. A jacket's role is just to provide a thermal barrier. It doesn't create warmth. It prevents body heat from escaping and "keeps out" cold air (Technically it's all heat traveling at a thermodynamics level). So the warmer you and the jacket start, the warmer a jacket will feel when you first put it on.

Is it possible to have a jacket that is so warm that you don't need to exert yourself first, but you can still be warm standing/sitting in the cold?

Your body is always generating heat. When you're active you just generate more heat than when you are still. So, yes, it is possible to have a warm enough jacket that you can be still and still stay warm. Many companies make synthetic "belay parkas" that are designed for exactly this while belaying climbers. They are 150-200g/m^2 insulated jackets that are oversized to fit over top of other layers while standing still on cold belays. Most people have no such use for these jackets.

So what jacket should you get? For standing around in 0C I'd actually recommend something around the warmth of the Patagonia down sweater you currently own. My Cerium LT with a similar amount/fill-power down keeps me happy at those temps. If you are still cold you could look at something with more fill, or just throw on a layer underneath.

  • I'm comparing the down sweater and the DAS parka. The down sweater has 150g of 800FP down, so 120k. The DAS parka has 173g total of Primaloft Gold, I have seen various sources say primaloft gold is equivalent to ~550FP, which is 95150. But reviews suggest the DAS parka is vastly warmer, outdoor crunch says -15C vs the sweater's -5C. Is there something missing from that calulcation? Even assuming primaloft = 800 still doesn't make the figures very different.
    – Tom
    Commented Jan 23, 2023 at 21:53
  • Down sweater is only 85g -> 68k. The DAS is definitely spec'd warmer, so I'm not surprised it is reviewed warmer. The DAS falls into the "belay jacket" category I mentioned. Source of 85g: patagonia.com/stories/from-the-tren-1/story-20227.html
    – noah
    Commented Jan 23, 2023 at 22:29
  • I did see that post but I took it to be an old one as it mentions a few product lines that don't exist anymore. I was basing it on this review: switchbacktravel.com/best-down-jackets, which cites 5oz/141g.
    – Tom
    Commented Jan 23, 2023 at 23:50
  • Oh, interesting. Looks like they've upped it (a lot) in the last year. That's surprising how much they've increased it. 5oz puts it in a somewhat different jacket category. It's a bit of an odd change imo. I'd make sure the one you've been using is the newer model before you assume 5oz though. Maybe the down sweater is now warmer than the DAS. The reviews across the web just might not be updated with the newest Down Sweater design
    – noah
    Commented Jan 24, 2023 at 0:41
  • I've emailed them to confirm as the numbers online are somewhat inconsistent. I bought both the DAS and the down sweater to test out in the current weather. I just went for a gentle stroll in the DAS and while it was tolerable, I didn't get warm and cosy either which seems odd to me given that I've seen reviews saying people feel toasty when it's blowing a gale at -15C and they're stood still belaying. I'm wondering if this Decathlon decathlon.co.uk/p/men-s-mountaineering-down-jacket-makalu-red/_/… jacket might be what I need which comes out at 165200.
    – Tom
    Commented Jan 24, 2023 at 1:02

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